package Usb_Usage;public class KeyBoard implements Usb{    @Override    public void Start() {        System.out.println("键盘启动！");    }    @Override    public void Over() {        System.out.println("键盘关闭！");    }    void Knock()    {        System.out.println("键盘敲烂，月薪过万！敲敲敲！");    }}